In the past, different aerosol formulations have been used to deliver atomized oil particles. One type of aerosol composition contained an oil, co-solvent and propellant typically for dispensing a small amount of an oil, such as a perfume. A second type of aerosol used simply an oil and propellant. These aerosols were called dry systems because the components vaporized upon spraying. A third type of aerosol is an aqueous based system which complies with EPA Regulations for Volatile Organic Compounds (VOC) primarily because they have water as the major component. One of the major problems with an aqueous aerosol has been the need to shake the system before use, just as when one mixes oil and vinegar they separate, the same thing occurs with this system. Typically, a "shake before using" statement is on the label of these products to avoid spraying only one phase through the dip tube of the spray can while the other phase remains in the can. In many cases, it is not practical or possible to shake the container before use and, thus, these systems have limitations. Where room air fresheners are formulated employing the three types of aerosols, usually about 25-50% of a perfume is contained in the first type, about 2-10% perfume is contained in the second type, and the third type usually contains about 1% perfume.
Two main types of water-based aerosols have been known, namely, a three-phase system and a two-phase system. The three-phase aerosol system is formed when using a propellant such as propane or butane which is insoluble in the water phase. These three-phase aerosol systems need to be shaken properly before use. Two-phase aqueous aerosol systems consist of a homogeneous liquid phase and a gaseous phase. The liquid phase usually contains the active ingredients, solvents and liquified propellant. Homogeneity is achieved by means of a water soluble propellant such as dimethyl ether (DME). These types of aerosols need not be shaken before use. However, it has been difficult to obtain homogeneous DME-water mixtures which are stable upon standing. Attempts have been made to solve the stability problem by developing special perfumes or by the addition of special solvents. U.S. Pat. No. 4,382,078 is an example of a prior approach to solve the stability problem by employing a copolymer of ethylene oxide and propylene oxide as a surfactant to retain the active ingredients in the liquid phase.
Furthermore, in this '078 patent, with increasing amounts of fragrance oil, increasing amounts of surfactant are required. Increased surfactant results in non-volatile material being sprayed which is undesirable because of unwanted deposition on surfaces, among other environmental deficiencies.
There exists a need for an aqueous aerosol composition for the delivery of atomized oil such as a fragrance oil, insecticidal oil and medicinal oil without the disadvantages associated with presently available systems.